Generally, optical sensors are to convert energy of light or electromagnetic waves into electric energy. Background-art optical sensors include photodiodes, avalanche photodiodes, phototransistors, photo-MOSs, CCD sensors and CMOS sensors having semiconductor as their main components, photomultiplier tubes using photoelectric effect, etc.
Of the former semiconductor optical sensors, some are to extract output signal as electric current by converting carriers into the external electric current directly, where the carriers are electron or positive holes generated by irradiation with light. Others are to extract output signal as a modulation of majority electric-current, where the modulation is formed by a local electric field by the photo-generated carriers accumulated in a predetermined local place.
As proposals of sensors using carbon nanotubes or as reports about optical properties of carbon nanotubes, the following patent documents and non-patent documents can be listed.
(Patent Document 1) JP-A-2003-517604
(Non-Patent Document 1) J. Kong, N. R. Franklin, C. Zhou, M. G. Chapline, S. Peng, K. Cho, H. Dai, ‘Nanotube Molecular Wires as Chemical Sensors’, Science Vol. 287 (January 2000) P. 622-625
(Non-Patent Document 2) P. G. Collins, K. Bradley, M. Ishigami, A. Zettl, ‘Extreme Oxygen Sensitivity of Electronic Properties of Carbon Nanotubes’, Science Vol. 287 (January 2000) P. 1801-1804
(Non-Patent Document 3) I. A. Levitsky, W. B. Euler, ‘Photoconductivity of single-wall carbon nanotubes under continuous-wave near-infrared illumination’ Applied Physics Letters, Vol. 83 (September 2003) P. 1857-1859